Air compressor safety valve keeps purging

Just started recently on my 2003 Detroit DDEC4 engine.

On the compression cycle, the safety valve on the compressor itself keeps purging air. The more RPM, the more frequent it is.

Checked air supply hose to air dryer: no kinks or bends. Took out the unloader valve: looks good, greased it up just in case put it back in, problem persists. On the "off" cycle, everything is okay.

Can the air dryer purge valve be the problem? Please help

 

Air pressure seems to be okay. Compressor kicks into compression mode around 105 psi and kicks off at around 130 psi.

One thing I did forget to mention is that the dryer purge valve doesn't purge air at end of the compression cycle. That's why I thought it was the purge valve that's bad.

Does the air pressure in the cabin get its info before or after the dryer? If after, maybe it is over 150 psi, and I'm just not seeing it on the gauges?

 

Governor, filter cartridge, purge valve all replaced about 1.5 years ago. By the way, it's a Bendix AD-IS dryer. Seems like I'm having 2 problems at once.

1. Compressor safety valve keeps popping on compression cycle although dash gauges show regular psi
2. Purge valve won't dump air out at 130 psi. The compressor somehow shuts off by itself without the valve purging.

 

Replaced air purge valve, problem solved. The old one had lots of crud and oil on it. Must have been stuck in the closed position, building up pressure.